@book { FourfamousCanadiansingers,
    title = "Four famous Canadian singers",
    author = "Johannes {Vees}",
    year = "2011",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783640990658",
    url = "https://www.hausarbeiten.de/document/175871"
}